Field of the Invention
The disclosed subject matter is directed to a bracing apparatus having a steel inner core element and the methods for fabrication of same. The present invention is useful in the construction of earthquake and blast resistant structures where energy dissipation is desired.
Description of the Related Art
Braced frames are commonly used in buildings and other structures to provide strength and stability against lateral forces induced by wind, earthquake, or other sources. Braced frames are also effective solution for limiting lateral displacement of building stories. Regardless of the arrangement of braces in braced frames (diagonal, chevron, etc.), the overall strength and stability of the lateral-force resisting system depends mainly on the performance of the structural braces. The buckling restrained brace frame (BRBF) is a highly ductile seismic-force resisting system intended primarily for special seismic applications. The principal advantage of the buckling restrained brace is that the brace does not buckle, so the brace strength is similar under compression and tension loading, which results in more economical use of framing members especially when compared to special concentric braced frames (SCBF). This is accomplished by attempting to decouple axial stresses from flexural buckling such that an inner steel core transfers axial load while the outer encasing buckling-restraining mechanism prevents global buckling and forces the core plate into local high-mode buckling. The preclusion of buckling in a restrained brace results in hysteretic behavior that is similar under both compression and tension loading. Another advantage of the buckling restrained brace frame is that the brace connections are relatively small and compact in comparison to the connections or special concentric braced frames.